It is known that two or more vehicles moving along a roadway can cooperate as a road train or a “platoon” for mutually providing to the vehicles within the platoon various safety and efficiency benefits. A typical vehicle platoon includes a leader vehicle and one or more follower vehicles arranged serially along a single roadway lane. More complicated platoons can span two or more roadway lanes but, overall, the goals of providing enhanced efficiency but more importantly safety to both the platooned vehicles as well as to the other non-platooning vehicles on the roadway most usually dictate the single lane platoon incarnation.
The aerodynamic geometry of the vehicles within a platoon is a significant factor used in determining an ordering of the vehicles. As a general rule, a physically smaller vehicle following a physically larger vehicle will provide a greater benefit. Since commercial box trucks and tractors towing box trailers are in general taller and wider than most flatbed tractor trailer combinations, a maximum aerodynamic benefit and resultant fuel savings is realized by ordering vehicles classified this way such that the commercial box truck and tractors towing box trailers take the leader position(s) in the platoon, while the flatbed tractor trailer rigs take the follower position(s) in the platoon.
In addition to the above, maintaining a small distance or spacing between platooned vehicles gives greater benefit in terms of reduced energy consumption. However, holding a tight distance or spacing between platooned vehicles requires that careful attention be paid to various functional or environmental and operational characteristics and capabilities of the vehicles and other external conditions including the overall size of the platoon, weather conditions, relative braking abilities between vehicle pairs, relative acceleration abilities, relative load or cargo size and weight including required stopping distance, and the like. Special attention must also be paid to characteristics of the roadway such as roadway incline, decline, and turn radii. These various parameters implicate directly or indirectly the inter-vehicle safety considerations as well as the overall safety of multiple vehicle platoons.
Although many commercial vehicles that participate in platoons are highly sophisticated and are equipped with adaptive cruise control (ACC) systems used for maintaining a safe relative distance between a host vehicle and a forward vehicle, and collision mitigation (CM) systems for avoiding or lessening the severity of impacts between a host and a forward vehicle using various combinations of transmission, vehicle retarder, and foundation brake controls, the vehicles are not completely autonomous. More particularly, humans drive commercial vehicles in platoons and current ACC and CM systems do not provide for inter-vehicle platoon distance and/or spacing management between platoon vehicle pairs.
One SAE standard is J2945 directed in general to Dedicated Short Range Communication (DSRC), and a work in process portion of that standard is J2945/6 is directed to performance requirements for cooperative ACC and platooning. J2945/6 is intended to define the data exchange that will be necessary for coordinated maneuvers, and that definition of the categories should start with differentiating between platooning and ACC, then determining message sets and performance to realize cooperative vehicles. However, J2945/6 also does not provide for inter-vehicle platoon distance management between platoon vehicle pairs.
Given the above, it will be helpful to use selected parameters relating to external conditions together with vehicle physical characteristics, performance information, and other factors to select an optimized minimum distance or spacing between vehicle pairs traveling as a platoon. It would be helpful for a following vehicle of the platoon vehicle pair to aggregate the parameters relating to the external or environmental conditions, and to use the aggregated and processed parameters to adjust or otherwise modify a predetermined minimum following distance or spacing parameter. This would allow enhanced flexibility in the platooning control to follow at different distances providing for maximized safety while yet maintaining an overall fuel economy benefit of the platoon.
The present embodiments provide for new and improved control of variable distances or spacing between vehicles in a platoon.